Man, I have the exact same thing going on under the chin but let me tell you you don't have to even wait. Your beard is good man, I saw the stubble (potential) under your chin and in your connectors. What I did is just give it time, what looks like nothing will grow and begin to thicken up. My connectors, underneath chin, and mustache all look inferior but when given time matured and looked just peachy. If you just grow it out, and keep growing it out, the patches will cover and the little hair will become fur balls. 

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